Centrifugal fan.



No. 865,962. PATENTED SEPT; 10,, 1907.

w. E. ALLINGTON. 'UENTRIFUGAL PAN.

APPLIOATION FILED JUNE 18. 1906:

2 SHEETS-SHEET 1.

No. 865,962. PATENTED SEPT. 10, 1907.

' Y W. E. ALLINGTON.

'GENTRIFUGAL FAN.

APPLICATION FILED JUNE 18. 1906.

2 S'HEETSSHEET 2..

' STATES WILLIA ALLINGTON, F SAGINAW, MICHIGAN.

. onnrnmuesr. Fair.

To all whom it may concern:

Be it known that 1, WILLIAM E. AIIJLIN\GTON, a citizen of the UnitedStates, residing at Saginaw, in the county of Saginaw and StateofMichigan, have invented oer-- tain new and useful Improvementsin'Centrifugal 'Fans, of which the following is a specification.

My invention relates to centrifug'alfans, and particularly to fans ofthe general type illustrated in my prior application, Serial l I Q.,,24-,3,2 O4, filed January 30th,1905. I

' The primary object of my invention is to provide character of materialto be handled, and is adapted to withstand the shocks and strainsincident to the handling of material of various qualities.

Yet a further object of my invention is to associate the fan'wheel withdriving means in such manner as to minimize the deleterious vibration ofthe fan wheel and driving means; I I i Other and further objects of myinvention will become apparent to those skilled in the art from thefol-' lowing description taken in conjunction with the accompanyingdrawing, wherein;

Figure 1 is a side view, with the casing broken away, of a fan embodyingmy invention. Fig. 2 is an end elevation, with part of the casing'andfan wheel broken away, of an embodiment ofmy invention. Figs. -3 and 4are details of two forms of blade structure suitableforiusefintheiembodiment of invention.

Throughout the drawings like numerals of reference refer always to likepartsj In the drawings, 5 indicates in general a scrollshapedfan'casing, whereof 6 is the front side having fit in the recess 9' ofthe fan casing, the motor-being therein an inlet 7; and 8 is. the rearside having therein a recess 9, alining with the inlet 7, and having acentral aperture l0 for the reception of the fan supporting shaft. I

11 indicates posed 12 indicates a driving means, illustrated as an electric motor, supported as on the bearing blocks 13 independently of thefancasing, and provided with a hub 14, as is usual in suchmotor'devices, arranged to the peripheraloutlet, tangentially disalsoprovided with the usual protruding shaft 15, which projects through theaperture-10 in the wall of .said

Specification of Letters Patent.

j Application filed June 18,1906; Serial No. 322,225.

Patented Sept.10, 1907;

recess 9 into the interior of the fan casing to support the fan wheel.This manner of mounting the motor Ihave found to be very advantageous,as it permits the use of standard motors-without providing extra longshafts and the supporting of the motor independently of the fan casingpreventsthe long-wave vibration of the diaphragm-like sides of the fancasing from being communicated to the motor mechanism or the fan wheelon the motor shaft. In referring tothe fan wheel I will advert to thewheel in general as having a front side, toward the inlet, a rear side?away from the inlet, and to the various blades incorporated in the fanwheel as each having a front face which is the forward surface of theblade with reference to the direction of rotation of the wheel, and arear face, which is the opposite surface of the blade. It will also beunderstood that in referring to radial blade parts, or arms, I mean,approximately. radial, as for convenience'devi'ces best arrangedradially are sometimes in this art built at a slight angle to trueradial position.

hub secured, as by set screws 17, to. the motor shaft annular disk 18,having a number of ribs 19, equal=to the number' of-blades of the wheel,formed thereon,

disposed, laterallysprojecting 'ribs 20, which serve froin' the ribs 19.To the disk 18 and ribs 19, are suitably secured radial angle iron arms21; in number corresponding to the num- 'ber of blades, and each havingriveted, or otherwise socured to its front flat face, a blade 22. Forconvenience the arms 2lare positioned in the mold, and'the centercasting cast around them, though other modes of attachment may besubstituted. Each blade 22, independently supported on an arm 21,preferably lies wardly deflected portion terminating in a delivery lip,which projects sharply forward with reference to the direction ofrotation of the wheel, to deliver air and ma terial therefrom into theclearance space surrounding the point of delivery, to the direction ofprogress of the air and material in flow past such point in theclearance space. To this end the forwardly deflected portion, as

23, and relatively shallow when compared withsaid rajecting at an obtuseangle to the intermediate portion drawn to the periphery of the wheel'atthe delivery edge 15, and preferably having integrally cast therewith anand having at intervals, on its front face only, radiallysome of thefunctions of narrow blades, and which- I willanbitrarily term'"projector" ribs for distinction wholly without the periphery ofthe disk18, and pro- I vides a relatively deep radial portion 23, and a for- 24,so that its rear face 'meets at an acute angle a tangent PATENT] orrronfp Referring to the wheel structure, 16" indicates the the wheel in adirection approximating parallelism at l illustrated in Fig. 3, maycomprise an intermediate part 24 forming a very obtuse angle with theradial portion I dial portion, and a still shallowerv lip portion 25,proof the end of the lip;'or the deflected portion may, as

shown in Fig.4, consist of a curved part 25 terminating in a deliverylip, disposed atsubstantially the same angle as thelip 'portion 25 ofthe first described blade.

The function of such a deflected structure is to form upon the bladeapocket for dead air, whereon the air in delivery curve, from radial tonearly tangential, so that the least possible resistance to the changeof direction may be encountered, and that when delivered to theclearance space the air and material may be flowing in a directiongenerally parallel to the direction of flow in the clearance space. As aresult back pressure in the fan is minimized, or conversely stated,efficiency of the fan islargel'y' increasedf I have found that thenearer "to true tangential the arrangement of the delivery lip thegreater the efiiciency of air delivery, but in a material handling fanit is necessary, in order to prevent undue pocketing of material, toarrange the delivery lip at a slight angle to true tangential; This Ihave found my be done without negativing or destroying the beneficialaction of the air pockets in the blades, but the particular angularityofthe deliverylip to true tangential, which may be provided withoutmaterial detriment to the action of the fan, is dependent somewhat onthe speed at which the fan is designed to run, the higher the '-speedthe greater being the latitude of angularity peri missible.

The blades 22 are mounted to extend on both sides of the plane of thesupporting arms 21, that is toward the front and rear sides of thecasing, the radially inner edge of each blade on the side of thesupporting arm toward the front of the casingbeing preferably cut away,as shown at 26, at such an angle to the horizontal as to permit stringymaterial,'which may lodge thereon, to slide radially off of the cut-awayedge under the influence of centrifugal force. The rear portion of theradially i nner blade-edge ispreferably also cut away somewhat, as shownat 28, so that the radially inner portion of the blade tapers toward theaxis of rotation through an area as generally shown at 29. I

To close the ends of the pockets formed by the deflected portion of theblades, adjacent the rear side of the casing, and further to prevent thepassage of material radially through the wheel to the rear sideof thecasing, I provide an annular plate 30 extending radially outwardto theends of the delivery lips of the blades and radially inward a suitabledistance, the central opening of the plate 30 being preferably not,greatly "larger than the diameter of the disk 18.

The width of the fan wheel, by which I mean its ex- -.tent from its rearside to its front side, is preferably considerably less than theinternal width of the casing,

and the wheel is mountedwith its rear side as close to the rear sidev 8of the fan casing as good practice will permit, sothat there is left awide clearance space on the front or inlet side of the casing, suchspace in width being preferably at least one third of the total width ofthe fan casing- 4 I'n'the operation of the fan, the wheel, set inrotation by its motor,- entrains air and material through the inlet 7.-Heavy pieces of material, such asblocks of wood and the like (where thefan is used for instance to han- 'dlere fuse from a woodworking mill,)strike the solid disk 18, or the narrowheels ofthe blades adjacentfsuchdisk, which is so substantially built as to withstand without injury theimpact of such material traveling at a relatively high velocity, "andprojector ribs 20 start such heavy articles in rotation and impartthereto an initial centrifugal action which relieves the Work of theblades proper 22. I By reason of the forward .defiection of the blades,as heretofore described, the air .and .material,, as delivered into theclearance space generally corresponding to the direction of travel ofthe air and material already in the clearance space, the pocket in theblade being of such configuration as to permit the air in flow past theblade to form its own delivery curve upon a body of substantially deadair carried in the pocket. The relation of the disk and back plate shownI have found effective in preventing material from passing through thewheel from its front side to its rear side in escape from the blade, asin somewhat affected. by centrifugal force, and I have found that as aresult material always is thrown outward at such an angle that theinneredg'e of the back plate 30 may be somewhat more remote from theaxis than the periphery of the disk. I

The'arrangement of the blades, in large number, not ,less than twelve, Ihave found advantageous for the reason among others, that the increasedefficiency, due to-the pocket structure of the bladesis lost in greateror less degree as the number of blades is decreased and I have found itto be practically impossible to obtain any material advantage by the useof a pocket con struction of blade where the blades number less thantwelve to the wheel, and in practice I prefer to employ sixteen or moreblades. Further the arrangement of the blades upon independent supportshas advantage, aside to the strength and rigidity imparted to the wheel,in that it enables me to dispense with any sort of connectionbetween theblades on the front side of eter without deleteriously efiecting theaction of the fan: i I I J N While I have herein described in somedetail aspecific embodiment of myinvention, which in actual practice Ihave found to be satisfactory in its operation, it will be understoodthat I' do not intend to limit my further than as specified in theclaims. I

Having thus described my invention, what I claim and desire to secure byLetters Patent of the United States, is: r

1. In a "centrifugal fan for handling material, the comblnation with afan casing, having an eye in its, side, of a the wheel, so that theinclined inner edges 26, of the blades join with the free front edges ofsaid blades and' invention to the specific details shown and describeperipherally without the wheel, travel in a direction I seeking toeffect such ,passage the material is always in connection with a casingof any given depth or diamnecting the back edges of the blades, and aseparate supporting arm for each blade connected with the radialmidportion of the blade and connected with the hub. v

2. In a centrifugal fan for handling material, the combination with afan-casing having an eye in its side, of a wheel comprising a hub, aplurality of blades-each free throughout its edge adjacent the inlet,and providing a' 3. In a centrifugal fan for handling-material, thecombination with a casing providing-an axial inlet and a pcripheraloutlet, of a wheel providing a central fiat disk alining with the inletto receive the impact of material entrained through the inlet, radialribs upon the face of said disk adjacent the inlet, and blades arrangedwholly,

beyond the disk.

4. In a centrifugal material handling fan, a casing, a

wheel open throughout on its front side, and comprising a plurality ofsupporting arms equal in number to the blades, a blade secured to eachsupporting arm, the radially inner edge-of'each of said blades beinginclined, from its point of juncture with the supportingarm toward thefront of the casing, to permit the centrifugal delivery of stringymaterial encountering the edge of the blade'toward the open front sideof the wheel.

5. In a material handling fan, a wheel comprising blades, each havingarelatively deep radial portion, a

forwardly deflected pocket portion adapted to contain a body ofsubstantially dead air whereon the air in flow past the blade may formits own curve from radial entry to approximately tangential delivery,each bladebeing free at its front side and shaped to provide a portionclosest to the inlet intermediate the tip and heel of the blade, thefront edge of the blade being inclined rearwardly from such point to itstip, means for closing' the rear sides of the pockets in the blades, andmeans for supporting the blades.

6. In combination, a suitable support,-a motor thereon having avprojecting shaft, a fan wheel mounted on the shaft. a fancasingsurrounding the said wheel providing a rear wall of relativelylarge area, having anaperture therein for the shaft, wherethroughsaidshaft projects out of contact with the wall, the middle area of saidwall,

susceptible to vibration due tothe action of the fan wheel,

WILLIAM E. ALLINGTON.

In the presence of MARY F. ALLEN, GEORGE '1. MAY, Jr.

